Condensed Matter Seminars

We consider a two species gas of fermions with population imbalance. Using the renormalisation group in d=1+ ε dimensions, we show that for spinless fermions and ε > 0 a fixed point appears at finite attractive coupling where the quasiparticle residue Ζ vanishes, and identify this fixed point with the transition to Larkin--Ovchinnikov--Fulde--Ferrell order (inhomogeneous superconductivity). When the two species of fermions also carry spin degrees of freedom we find a repulsive fixed point, indicating a transition to spin density wave order.